Differential Effect of Modified Medical Research Council Dyspnea, COPD Assessment Test, and Clinical COPD Questionnaire for Symptoms Evaluation Within the New GOLD Staging and Mortality in COPD

Abstract

Objective: The modified Medical Research Council (mMRC) dyspnea, the COPD Assessment Test (CAT), and the Clinical COPD Questionnaire (CCQ) have been interchangeably proposed by GOLD (Global Initiative for Chronic Obstructive Lung Disease) for assessing symptoms in patients with COPD. However, there are no data on the prognostic value of these tools in terms of mortality. We endeavored to evaluate the prognostic value of the CAT and CCQ scores and compare them with mMRC dyspnea. Methods: We analyzed the ability of these tests to predict mortality in an observational cohort of 768 patients with COPD (82% men; FEV1, 60%) from the COPD History Assessment in Spain (CHAIN) study, a multicenter observational Spanish cohort, who were monitored annually for a mean follow-up time of 38 months. Results: Subjects who died (n = 73; 9.5%) had higher CAT (14 vs 11, P = .022), CCQ (1.6 vs 1.3, P = .033), and mMRC dyspnea scores (2 vs 1, P < .001) than survivors. Receiver operating characteristic analysis showed that higher CAT, CCQ, and mMRC dyspnea scores were associated with higher mortality (area under the curve: 0.589, 0.588, and 0.649, respectively). CAT scores ≥ 17 and CCQ scores > 2.5 provided a similar sensitivity than mMRC dyspnea scores ≥ 2 to predict all-cause mortality. Conclusions: The CAT and the CCQ have similar ability for predicting all-cause mortality in patients with COPD, but were inferior to mMRC dyspnea scores. We suggest new thresholds for CAT and CCQ scores based on mortality risk that could be useful for the new GOLD grading classification.